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Synchronize access to data

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gion
2020-04-28 14:12:06 +02:00
parent 73fcbe90c0
commit 0b974d09ca
3 changed files with 216 additions and 147 deletions
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206
Emby.Server.Implementations/Session/SessionWebSocketListener.cs
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@@ -1,6 +1,5 @@
using System.Collections.Generic;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.Threading;
@@ -26,9 +25,9 @@ namespace Emby.Server.Implementations.Session
public readonly int WebSocketLostTimeout = 60;
/// <summary>
/// The keep-alive timer factor; controls how often the timer will check on the status of the WebSockets.
/// The keep-alive interval factor; controls how often the watcher will check on the status of the WebSockets.
/// </summary>
public readonly double TimerFactor = 0.2;
public readonly double IntervalFactor = 0.2;
/// <summary>
/// The ForceKeepAlive factor; controls when a ForceKeepAlive is sent.
@@ -53,14 +52,24 @@ namespace Emby.Server.Implementations.Session
private readonly IHttpServer _httpServer;
/// <summary>
/// The KeepAlive timer.
/// The KeepAlive cancellation token.
/// </summary>
private Timer _keepAliveTimer;
private CancellationTokenSource _keepAliveCancellationToken;
/// <summary>
/// Lock used for accesing the KeepAlive cancellation token.
/// </summary>
private readonly object _keepAliveLock = new object();
/// <summary>
/// The WebSocket watchlist.
/// </summary>
private readonly ConcurrentDictionary<IWebSocketConnection, byte> _webSockets = new ConcurrentDictionary<IWebSocketConnection, byte>();
private readonly HashSet<IWebSocketConnection> _webSockets = new HashSet<IWebSocketConnection>();
/// <summary>
/// Lock used for accesing the WebSockets watchlist.
/// </summary>
private readonly object _webSocketsLock = new object();
/// <summary>
/// Initializes a new instance of the <see cref="SessionWebSocketListener" /> class.
@@ -113,7 +122,7 @@ namespace Emby.Server.Implementations.Session
public void Dispose()
{
_httpServer.WebSocketConnected -= _serverManager_WebSocketConnected;
StopKeepAliveTimer();
StopKeepAlive();
}
/// <summary>
@@ -140,6 +149,7 @@ namespace Emby.Server.Implementations.Session
private void OnWebSocketClosed(object sender, EventArgs e)
{
var webSocket = (IWebSocketConnection) sender;
_logger.LogDebug("WebSockets {0} closed.", webSocket);
RemoveWebSocket(webSocket);
}
@@ -147,15 +157,20 @@ namespace Emby.Server.Implementations.Session
/// Adds a WebSocket to the KeepAlive watchlist.
/// </summary>
/// <param name="webSocket">The WebSocket to monitor.</param>
private async void KeepAliveWebSocket(IWebSocketConnection webSocket)
private async Task KeepAliveWebSocket(IWebSocketConnection webSocket)
{
if (!_webSockets.TryAdd(webSocket, 0))
lock (_webSocketsLock)
{
_logger.LogWarning("Multiple attempts to keep alive single WebSocket {0}", webSocket);
return;
if (!_webSockets.Add(webSocket))
{
_logger.LogWarning("Multiple attempts to keep alive single WebSocket {0}", webSocket);
return;
}
webSocket.Closed += OnWebSocketClosed;
webSocket.LastKeepAliveDate = DateTime.UtcNow;
StartKeepAlive();
}
webSocket.Closed += OnWebSocketClosed;
webSocket.LastKeepAliveDate = DateTime.UtcNow;
// Notify WebSocket about timeout
try
@@ -164,10 +179,8 @@ namespace Emby.Server.Implementations.Session
}
catch (WebSocketException exception)
{
_logger.LogWarning(exception, "Error sending ForceKeepAlive message to WebSocket.");
_logger.LogWarning(exception, "Error sending ForceKeepAlive message to WebSocket {0}.", webSocket);
}
StartKeepAliveTimer();
}
/// <summary>
@@ -176,88 +189,131 @@ namespace Emby.Server.Implementations.Session
/// <param name="webSocket">The WebSocket to remove.</param>
private void RemoveWebSocket(IWebSocketConnection webSocket)
{
webSocket.Closed -= OnWebSocketClosed;
_webSockets.TryRemove(webSocket, out _);
}
/// <summary>
/// Starts the KeepAlive timer.
/// </summary>
private void StartKeepAliveTimer()
{
if (_keepAliveTimer == null)
lock (_webSocketsLock)
{
_keepAliveTimer = new Timer(
KeepAliveSockets,
null,
TimeSpan.FromSeconds(WebSocketLostTimeout * TimerFactor),
TimeSpan.FromSeconds(WebSocketLostTimeout * TimerFactor)
);
if (!_webSockets.Remove(webSocket))
{
_logger.LogWarning("WebSocket {0} not on watchlist.", webSocket);
}
else
{
webSocket.Closed -= OnWebSocketClosed;
}
}
}
/// <summary>
/// Stops the KeepAlive timer.
/// Starts the KeepAlive watcher.
/// </summary>
private void StopKeepAliveTimer()
private void StartKeepAlive()
{
if (_keepAliveTimer != null)
lock (_keepAliveLock)
{
_keepAliveTimer.Dispose();
_keepAliveTimer = null;
}
foreach (var pair in _webSockets)
{
pair.Key.Closed -= OnWebSocketClosed;
if (_keepAliveCancellationToken == null)
{
_keepAliveCancellationToken = new CancellationTokenSource();
// Start KeepAlive watcher
KeepAliveSockets(
TimeSpan.FromSeconds(WebSocketLostTimeout * IntervalFactor),
_keepAliveCancellationToken.Token);
}
}
}
/// <summary>
/// Checks status of KeepAlive of WebSockets.
/// Stops the KeepAlive watcher.
/// </summary>
/// <param name="state">The state.</param>
private async void KeepAliveSockets(object state)
private void StopKeepAlive()
{
var inactive = _webSockets.Keys.Where(i =>
lock (_keepAliveLock)
{
var elapsed = (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds;
return (elapsed > WebSocketLostTimeout * ForceKeepAliveFactor) && (elapsed < WebSocketLostTimeout);
});
var lost = _webSockets.Keys.Where(i => (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds >= WebSocketLostTimeout);
if (inactive.Any())
{
_logger.LogDebug("Sending ForceKeepAlive message to {0} inactive WebSockets.", inactive.Count());
if (_keepAliveCancellationToken != null)
{
_keepAliveCancellationToken.Cancel();
_keepAliveCancellationToken = null;
}
}
foreach (var webSocket in inactive)
lock (_webSocketsLock)
{
foreach (var webSocket in _webSockets)
{
webSocket.Closed -= OnWebSocketClosed;
}
_webSockets.Clear();
}
}
/// <summary>
/// Checks status of KeepAlive of WebSockets once every the specified interval time.
/// </summary>
/// <param name="interval">The interval.</param>
/// <param name="cancellationToken">The cancellation token.</param>
private async Task KeepAliveSockets(TimeSpan interval, CancellationToken cancellationToken)
{
while (true)
{
_logger.LogDebug("Watching {0} WebSockets.", _webSockets.Count());
IEnumerable<IWebSocketConnection> inactive;
IEnumerable<IWebSocketConnection> lost;
lock (_webSocketsLock)
{
inactive = _webSockets.Where(i =>
{
var elapsed = (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds;
return (elapsed > WebSocketLostTimeout * ForceKeepAliveFactor) && (elapsed < WebSocketLostTimeout);
});
lost = _webSockets.Where(i => (DateTime.UtcNow - i.LastKeepAliveDate).TotalSeconds >= WebSocketLostTimeout);
}
if (inactive.Any())
{
_logger.LogInformation("Sending ForceKeepAlive message to {0} inactive WebSockets.", inactive.Count());
}
foreach (var webSocket in inactive)
{
try
{
await SendForceKeepAlive(webSocket);
}
catch (WebSocketException exception)
{
_logger.LogInformation(exception, "Error sending ForceKeepAlive message to WebSocket.");
lost = lost.Append(webSocket);
}
}
lock (_webSocketsLock)
{
if (lost.Any())
{
_logger.LogInformation("Lost {0} WebSockets.", lost.Count());
foreach (var webSocket in lost.ToList())
{
// TODO: handle session relative to the lost webSocket
RemoveWebSocket(webSocket);
}
}
if (!_webSockets.Any())
{
StopKeepAlive();
}
}
// Wait for next interval
Task task = Task.Delay(interval, cancellationToken);
try
{
await SendForceKeepAlive(webSocket);
await task;
}
catch (WebSocketException exception)
catch (TaskCanceledException)
{
_logger.LogInformation(exception, "Error sending ForceKeepAlive message to WebSocket.");
lost.Append(webSocket);
return;
}
}
if (lost.Any())
{
_logger.LogInformation("Lost {0} WebSockets.", lost.Count());
foreach (var webSocket in lost)
{
// TODO: handle session relative to the lost webSocket
RemoveWebSocket(webSocket);
}
}
if (!_webSockets.Any())
{
StopKeepAliveTimer();
}
}
/// <summary>